1. Field of the Invention
This invention relates to fluid discharge nozzles, and more particularly to a fluid discharge nozzle having a nozzle tip defining a spout for jetting out, at a jet angle, fluid such as liquid, gas or a mixture of liquid and gas.
2. Description of the Related Art
A fluid discharge nozzle of the type that jets out a mixture of liquid and gas is used, for example, to spray a mixture of pressurized water and pressurized air toward rolled steel plate to cool the steel, or to spray a mixture of water and chemical to plants in vegetable gardens or orchards. A nozzle of the type that jets out only gas is used, for example, to jet out air toward a steel surface to remove therefrom water, oil, stains and the like, or to dry the steel surface, or to cool the steel in a heat treatment. A nozzle of the type that jets out only liquid is used, for example, to jet out pressurized water toward a surface of rolled steel plate to remove scales therefrom.
Such a fluid discharge nozzle is required to jet out fluid with a maximum degree of dispersion while maintaining a jet pattern at a predetermined jet angle toward a transversely elongated or circular region selected according to a use mode. That is, the fluid is required to jet out with little density variations in a given position within a jetting region.
Where, for example, a mixture of pressurized water and pressurized air is sprayed in a thin flat jet pattern toward rolled steel plate to cool the steel plate, the mixture is required to jet out with water particles dispersed as much as possible. The steel plate tends to be quenched locally to affect its quality if the density of water particles is high in a middle position in a direction of spray thickness in the jetting region, and low in peripheral positions thereof.
FIGS. 26 through 28 show a conventional fluid discharge nozzle designed to meet the above requirement.
This fluid discharge nozzle has a slit-like spout 01 formed in a nozzle body 02 for spraying a mixture E of water and air in a flat sector pattern. The spout 01 is surrounded by an outlet edge 03 continuous to spray guide surfaces 04 diverging radially outward in a downstream direction of the jet. The mixture E jetting out of the spout 01 is guided by the spray guide surfaces 04. Water particles are dispersed toward the spray guide surfaces 04, i.e. outward in a direction of spray thickness perpendicular to the longitudinal direction of the spout 01, with expansion of the air from a compressed state and by a dispersing action of negative pressure regions 05 occurring on the spray guide surfaces 04 as a result of air discharge from the spout 01. The mixture E jets out in a well dispersed state while maintaining the flat sector jet pattern. (See Japanese Patent Publication Kokai S62-114673, for example.)
The conventional construction utilizes the dispersing action of negative pressure regions 05 resulting from the fluid discharge through the spout 01 as noted above. However, ambient air flows 06 generated by the discharge of fluid E from the spout 01 tend to move along the spray guide surfaces 04 toward the spout 01 since the negative pressure regions 05 occur on the spray guide surfaces 04 continuous from the outlet edge 03 of the spout 01 and diverging radially outward in the downstream direction of the jet. Thus, strong negative pressure regions 05 are problematic. Then, where, for example, a mixture of pressurized water and pressurized air is sprayed in a thin flat jet pattern, water particles cannot be dispersed sufficiently in the direction of spray thickness. That is, the fluid E cannot be sprayed in an effectively dispersed state by positively using the dispersing action of the negative pressure regions 05 while maintaining the desired jet pattern.
Moreover, since the negative pressure regions 05 are formed downstream of the outlet edge 03 of the spout 01, the fluid E jetting out of the spout 01 tends to move past the negative pressure regions 05 without being sufficiently drawn thereto. In this sense also, the fluid E cannot be sprayed in an effectively dispersed state by positively using the dispersing action of the negative pressure regions 05.